Silencing CHALCONE SYNTHASE in Maize Impedes the Incorporation of Tricin into Lignin and Increases Lignin Content

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Eloy, Nubia B. ; Voorend, Wannes ; Lan, Wu ; Saleme, Marina de Lyra Soriano ; Cesarino, Igor ; Vanholme, Ruben ; Smith, Rebecca A. ; Goeminne, Geert ; Pallidis, Andreas ; Morreel, Kris ; Nicomedes, Jr., Jose ; Ralph, John ; Boerjan, Wout

• Tipo de documento: Artigo Científico
• Fonte: Plant Physiology; v. 173, n. 2, p. 998-1016, FEB 2017.
• Citações Web of Science: 23

Resumo

Lignin is a phenolic heteropolymer that is deposited in secondary-thickened cell walls, where it provides mechanical strength. A recent structural characterization of cell walls from monocot species showed that the flavone tricin is part of the native lignin polymer, where it is hypothesized to initiate lignin chains. In this study, we investigated the consequences of altered tricin levels on lignin structure and cell wall recalcitrance by phenolic profiling, nuclear magnetic resonance, and saccharification assays of the naturally silenced maize (Zea mays) C2-Idf (inhibitor diffuse) mutant, defective in the CHALCONE SYNTHASE Colorless2 (C2) gene. We show that the C2-Idf mutant produces highly reduced levels of apigenin-and tricin-related flavonoids, resulting in a strongly reduced incorporation of tricin into the lignin polymer. Moreover, the lignin was enriched in beta-beta and beta-5 units, lending support to the contention that tricin acts to initiate lignin chains and that, in the absence of tricin, more monolignol dimerization reactions occur. In addition, the C2-Idf mutation resulted in strikingly higher Klason lignin levels in the leaves. As a consequence, the leaves of C2-Idf mutants had significantly reduced saccharification efficiencies compared with those of control plants. These findings are instructive for lignin engineering strategies to improve biomass processing and biochemical production. (AU)

• Processo FAPESP: 15/02527-1 - Desenvolvimento de sistemas-modelo em sorgo e uso da biologia de sistemas na elucidação dos mecanismos moleculares do metabolismo fenólico e de lignina em gramíneas
• Beneficiário: Igor Cesarino
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOEN - Jovens Pesquisadores